What does the 1-year warranty actually cover?

Covers manufacturing defects under normal use: LED chip failure Cooling system malfunction (fan/heatsink) Electrical faults (resistor/CANBUS issues) Does not cover physical damage, incorrect installation, corrosion, or water ingress from broken housings.

Do you offer free shipping?

Yes, we offer free shipping on orders over $89.

Are these bulbs energy efficient?

Yes, they consume 90% less power than traditional bulbs, making them energy-efficient and eco-friendly.

Does our rear brake and turn signal bulb with built in resistors work on taillights with 2 bulbs in each tail light?

Yes, ours is unique and different from other competitors. Unlike other brands out there that don't work, ours will. We specially designed the circuit board to work with the BCM.

Does this aftermarket LED replacement bulb with built in resistors get hotter than the OEM bulb?

No, the LED does get hot, but not as hot as an incandescent bulb.

Will the LED burn or melt the lens of my headlight or tail light?

No LEDs run cooler than OEM bulbs and will not harm or cause any damage to your wiring harness or housings. And our LEDs have an advanced cooling system, making it efficient and durable with a lifespan of 25k+ hours

I got my LED with built in resistors and I still have hyper flash why?

Did you start the engine before testing? The vehicle engine must be on and running for the BCM to turn on for the load resistors to be detected. Read the Hyperflash guide & know the details

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SKU: Wt21-W

2021+ Ford F-150 STX White LED Reverse Backup Bulbs With Built-in Resistors, No Error Codes (PAIR)

Name: 2021+ Ford F-150 STX White LED Reverse Backup Bulbs With Built-in Resistors, No Error Codes (PAIR)
Brand: Underground Lighting
SKU: Wt21-W
Price: 64.99 USD
Availability: InStock
Rating: 5.00 (5 reviews)

$64.99 $69.99

Popular right now
Lots of people have looked at this recently

300% brighter than halogen for clearer reversing
4257 / WT21 bulb design for the compatible F-150 application
1200 lumens per bulb with 54 SMD LEDs and 360° light coverage
Built-in resistor prevents CANBUS error codes
Advanced cooling extends lifespan up to 10× longer
Plug & play design, zero wiring required
Designed in the USA, assembled with Japanese components

Live Chat With a Qualified Expert

Description

Brighter Reverse Lights for Your Ford F-150 STX

Upgrade the factory halogen reverse lights on your Ford F-150 STX with a brighter white LED replacement. These 4257 / WT21 LED bulbs produce 1200 lumens per bulb through 54 SMD LEDs, giving you wider illumination when backing up, parking, or using your rear camera at night.

The 4257 LED bulb with a built-in resistor is designed to work with the truck's CANBUS system without extra resistors or wiring. The 360-degree output spreads light across the reverse-light housing instead of concentrating it in one direction.

1200-Lumen White LED Output

Each bulb uses 54 SMD LEDs to produce 1200 lumens of crisp white light with 360-degree coverage. The wider output helps illuminate more of the area behind the truck when reversing.

Built-in Resistor With CANBUS Compatibility

Modern vehicle electronics can detect changes in bulb load when replacing incandescent bulbs with LEDs. But Underground Lighting 4257 LED comes with a built-in resistor and CANBUS-compatible electrical design to help prevent error codes without adding external components.

Cooling for Consistent Performance

A full metal heatsink and built-in cooling fan help manage heat during operation. The fan activates when needed to support stable LED performance.

4257 / WT21 Direct Replacement

The bulbs use the 4257 / WT21 configuration for compatible Ford F-150 applications. The nonpolar design makes installation straightforward without needing to match bulb polarity.

Plug-and-Play Installation

Installation is simple and may take as little as 10 minutes. Remove the factory reverse bulb, install the LED replacement, and reconnect the socket. No cutting, splicing, or external resistor installation is required.

What's Included

What's Included
Warranty	This product comes with a 1-year warranty. Check the applicable Terms and Conditions for details.

Product Information

Function: Reverse / Backup Light
Bulb Variant: 4257 / WT21
LED Chips: 54 SMD LEDs
Beam Angle: 360° Coverage
Color: White
Cooling System: Fan + Metal Heatsink
Electrical Design: CANBUS, Nonpolar, CK Compatible
Error Codes: No, built-in resistor
Voltage: 12V DC
Installation: Plug-and-Play
Quantity: Pack of 2

Tech Specs

Tech Specs
Wattage	24W
Intensity	1200 Lumens per bulb

Warranty Information

This product comes with a 1-year warranty. Check the applicable Terms and Conditions for details.

Frequently Asked Questions (FAQ)

Do these bulbs fit the 2021 Ford F-150 STX?

Yes. These bulbs are designed for the reverse/backup light application on compatible 2021 Ford F-150 STX models.

Do these LED reverse bulbs cause error codes?

The bulbs use a built-in resistor and CANBUS-compatible electrical design to help prevent error codes without additional resistors.

Are these reverse light bulbs plug-and-play?

Yes. Bulbs are designed as a plug-and-play replacement with no cutting, splicing, or additional resistor installation required.

How much does the Ford F-150 STX LED reverse backup bulbs replacement cost?

The replacement costs $64.99 per pair and includes 2 white LED reverse backup bulbs with built-in resistors, plus a 1-year warranty.

Compatibility

Compatibility
Cross-compatibility	4257 / WT21
Fitments	2023 Ford F150 STX – Backup Light, 2023 Ford F-150 – Backup Light, 2022 Ford F150 STX – Backup Light, 2021 Ford F150 STX – Backup Light, 2022 Ford F-150 – Backup Light, 2021 Ford F-150 – Backup Light

Payment & Security

Payment Methods

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.

45 Day Returns

Hassle-free & easy
Talk to a Specialist

Call us (561) 918-5225
Free Shipping

On orders over $99.99
Ships Same Day

If order is placed before 2PM EST

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Nice upgrade!

I purchased the bulbs with others, for my brake lights and turn signals. They lived up to expectations and I’m going to order more soon!

2021 Ford F150 STX Replacement lights to LED

Underground Lighting answered all the questions I had regarding their products. Replaced front and rear turn signals, brake lights and reverse lights. Plug and play without hyper flash as described. Awesome option for the 2021 Fords that limit your options. Lights are much brighter than stock halogen. Shipping was next day. Only been in a short time to see what the lifespan will be, but at this rate, will definitely use this company again. Thank you!

2023 F150 STX 4x4

The back up lights is exactly what I was looking for. Just as good and bright as their stop light leds and turn signal leds.

Great

2022 F-150 Halogen to LED Conversion

These LED's are fantastic!! Very easy to install, super bright and instant on/off. I can't believe Ford is still using halogen, but as long as they do, you can go to Underground Lighting to modernize your truck!

Is this bulb compatible with the reverse light on the XLT trim?

Underground Lighting

Hi Ron,
No this will not fit the XLT trim. The XLT trim has factory LEDs already in the reverse light. Which is a sealed led board, not a bulb.